The present invention relates to a refrigerant cycle unit for air-conditioning and dehumidifying a space to be air-conditioned by causing a refrigerant to give off heat or absorb heat in a utilizing side heat exchanger arranged to be capable of heat exchanging with the space to be air-conditioned.
Heretofore, as shown in FIG. 11 a refrigerant cycle unit of this kind, for example, a car air-conditioner for air-conditioning and dehumidifying the interior of an automobile includes a refrigerant circuit comprising a compressor 204, a utilizing side heat exchanger 201 arranged to be capable of heat exchanging with the interior of a car as an air-conditioned space, a heat source side heat exchanger 203 arranged outside the interior of the car, flow regulating valves 211, 212 and 213, and the like.
As shown in FIG. 12, the utilizing side heat exchanger 201 is formed with blow-off openings 200A directing into three directions of lower foot Fo, front face Fa and glass surfaces De such as a windshield (not shown in FIG. 11) and is arranged in a storage room 200 provided to be capable of heat exchanging with the interior of the car. Arranged on the opposite side from the blow-off openings 200A with respect to a utilizing side heat exchanger 201 in the storage room 200 is a blower 210 for feeding the air in the interior of the car to the utilizing side heat exchanger 201 and further feeding the air which has been heat exchanged with a refrigerant in the utilizing side heat exchanger 201 through the blow-off openings 200A into the interior of the car.
The utilizing side heat exchanger 201 comprises an internal gas cooler 202 for causing the refrigerant compressed in the compressor 204 to give off heat, and an evaporator 209 for causing the refrigerant decompressed in a flow regulating valve 212 to absorb heat. The internal gas cooler 202 is arranged on the side of the blow-off openings 200A in the storage room, while the evaporator 209 is on the side of the blower 210. Arranged on the rear side of the internal gas cooler 202 in the storage room (on the side of the evaporator 209) is a movable deflector 205 which can be turned in both directions about a shaft 214 provided substantially at a middle in a vertical direction in the storage room 200.
As shown in FIG. 12, moreover, when the deflector 205 is positioned on the back surface of the internal gas cooler 202, the gas fed to the internal gas cooler 202 by the blower 210 is shut off by the deflector 205 so that the refrigerant hardly gives off heat in the internal gas cooler 202. As shown in broken lines in FIG. 12, moreover, when the deflector 205 is positioned above the internal gas cooler 202, the deflector 205 does not shut off the gas flow to the internal gas cooler 202 so that the refrigerant and the air fed from the blower 210 are heat exchanged with each other in the internal gas cooler 202. Therefore, the air heated by the heat given off from the refrigerant is fed through the blow-off openings 200A into the interior of the car.
The operation of the car air-conditioner of the prior art shown in FIGS. 11 and 12 will be presently explained. First, a heating mode for heating the interior of the car will be explained. In this case, the deflector 205 is positioned above the internal gas cooler 202 as shown in broken lines in FIG. 11, and the flow regulating valve 211 is throttled so as to effect decompression in the flow regulating valve 211. Further, the flow regulating valve 212 is completely closed, while the flow regulating valve 213 is fully opened so that the flowing of the refrigerant into the evaporator 209 is impeded.
First, the air compressed in the compressor flows into the internal gas cooler 202 to be heat exchanged with the ambient air and to give off heat. At this time, the air heated by being heat exchanged with the refrigerant in the internal gas cooler 202 is fed by the blower 210 through the blow-off openings 200A into the interior of the car, thereby heating the interior of the car.
On the one hand, the refrigerant which has given off heat in the internal gas cooler 202 is decompressed in the flow regulating valve 211 and thereafter flows into a heat source side heat exchanger 203 where the refrigerant absorbs heat and is evaporated. Thereafter, the refrigerant flows through the flow regulating valve 213 and is sucked into the compressor 204 and subsequently such a cycle is repeated.
A cooling mode for cooling the interior of the car will then be explained. In this case, the deflector 205 is positioned on the back surface of the internal gas cooler 202 as shown in FIG. 12. Moreover, the flow regulating valve 211 is fully opened, and the flow regulating valve 212 is throttled to permit the refrigerant to be decompressed, while the flow regulating valve 213 is completely closed. Then, the refrigerant compressed in the compressor 204 flows into the internal gas cooler 202. In this case, because of the impediment to the gas flow from the blower 210 by the deflector 205 positioned on the back surface of the internal gas cooler 202 in the cooling mode, the refrigerant hardly gives off heat in the internal gas cooler 202 and flows into the heat source side heat exchanger 203.
The refrigerant flown into the heat source side heat exchanger 203 is heat exchanged with the ambient air so as to give off heat and thereafter the refrigerant is decompressed in the flow regulating valve 212 and absorbs heat to be evaporated in the evaporator 209. At this time, the air cooled by heat exchanging with the refrigerant is forced by the blower 210 through the blow-off openings 200A into the interior of the car, thereby cooling the interior of the car. On the other hand, the refrigerant which has absorbed the heat and evaporated in the evaporator 209 is sucked into the compressor, and subsequently such a cycle is repeated.
An operating mode for eliminating mist on glasses occurring in winter or the like will then be explained, that is, a dehumidifying heating mode for dehumidifying the interior of a car, while heating the interior. In this case, the deflector 205 is positioned above the internal gas cooler 202. Moreover, the flow regulating valves 211 and 212 are throttled to permit the refrigerant passing through these valves to be decompressed, while the flow regulating valve 213 is completely closed.
The refrigerant compressed in the compressor 204 gives off heat in the internal gas cooler 202 and is decompressed in the flow regulating valve 211, and the refrigerant absorbs heat in the heat source side heat exchanger 203. The refrigerant discharged from the heat source side heat exchanger 203 is further decompressed in the flow regulating valve 212 and thereafter flows into the evaporator 209 so as to absorb heat and to be evaporated. At this time, the air circulating in the interior of the car with the aid of the blower 210 is cooled during the stage of passing through the evaporator 209, whereby moisture is removed from the air and hence the air is dehumidified. The dehumidified air is fed by the blower 210 into the internal gas cooler 202 where the air is heat exchanged with the refrigerant so as to be heated, and thereafter the heated air is fed through the blow-off openings 200A into the interior of the car. In this way, the evaporator 209 and the internal gas cooler 202 are arranged in the storage room provided to be capable of heat exchanging with the interior of the car. In this case, the evaporator 209 is arranged on the side of the blower 210, while the internal gas cooler 202 is arranged on the side of the blow-off openings 200A to be closer thereto than the evaporator 209 so that the air in the interior of the car is cooled in the evaporator 209 and moisture is condensed and removed from the air and, thereafter, the air is heated in the internal gas cooler 202. In this manner, the dehumidifying heating mode is carried out by heating the air, while dehumidifying the air (refer to, for example, official gazette of Japanese Patent Application Laid-Open No. 19,443/2002).
Meanwhile, in the event that the movable deflector 205 is provided in the storage room 200, and the heating, cooling and dehumidifying heating for the interior of a car are carried out by controlling the deflector 205, a space in the storage room is required for accommodating the deflector 205 and means for moving it so that the capacity of the utilizing side heat exchanger 201 must be correspondingly smaller because the space is limited for installation as is the case with a car air-conditioner. Therefore, this system of the prior art suffers a disadvantage from lowered the cycle efficiency.
In the refrigerant circuit of the prior art described above, moreover, as the refrigerant which has absorbed heat in the heat source side heat exchanger 203 flows into the evaporator 209 in the dehumidifying heating mode, it is difficult to accurately adjust the evaporating amount of the refrigerant in the evaporator 209. In other words, if the evaporating amount of the refrigerant in the evaporator 209 is little, the dehumidifying effect in the evaporator 209 would become insufficient so that there is a risk of driving being disturbed because the mist on glasses cannot be rapidly removed. On the one hand, when the evaporating amount of the refrigerant in the evaporator 209 increases, although the dehumidifying effect can be sufficiently obtained, a problem would occur such that the interior of the car cannot be effectively heated due to increased air amount to be heat exchanged with the refrigerant in the evaporator 209.
In recent years, moreover, in order to reply to the global environmental problems, it has been attempted to use CO2 (carbon dioxide) as a natural refrigerant without using conventional Freon gas and to operate the system so as to enable the pressure of the refrigerant on high pressure side to be supercritical pressure. In the case that the carbon dioxide is used and its high pressure side is at the supercritical pressure, the heating performance for the interior is affected by the temperature at the outlet of the internal gas cooler. When the temperature in a room is lower in heating, also the temperature at the outlet of the internal gas cooler becomes lower so that improved heating performance can be expected. In cooling, however, the gas cooler as the heat source side heat exchanger must be heat exchanged with the outdoor air at high temperatures so that the temperature at the outlet could not be lowered, which would make it difficult to exhibit sufficient cooling performance.
In order to solve the above problem, it has been attempted to provide an internal heat exchanger in a refrigerant circuit for heat exchanging the refrigerant on high pressure side which has given off heat but is prior to being decompressed and the refrigerant on the low pressure side which has absorbed heat but is prior to being sucked into the compressor. Using such an internal heat exchanger, in the cooling mode it becomes possible to cause the refrigerant to give off much more heat by heat exchanging the refrigerant which has given off heat in the internal gas cooler with the refrigerant on the low pressure side so that the temperature of the gas cooler as the heat side heat exchanger can be lowered, thereby enabling a desired cooling performance.
In the internal heat exchanger of the prior art, however, as the refrigerants in both the heating and cooling modes pass through the same flow passages, if the heat exchanged amount of the refrigerant in the internal heat exchanger is set to an optimum value for the cooling mode, the temperature of the refrigerant on the low pressure side in the heating mode would become a higher temperature by the heat exchange in the internal heat exchanger, thereby resulting in a problem of extraordinary rise of delivery temperature of the refrigerant compressed in the compressor. As a result, various problems occur in a manner that the oil in the compressor would be degraded and the compressor and other peripheral devices are adversely affected. Moreover, materials for appliances arranged in the refrigerant circuit on the high pressure side must be selected to tolerate such high temperatures so that the material choice would become difficult.
It is an object of the invention to provide a refrigerant cycle unit which solves the technical problems with the prior art and which can ensure a sufficient capacity of a utilizing side heat exchanger and is capable of smoothly dehumidifying and heating a space to be air-conditioned.
It is another object of the invention to provide a refrigerant cycle unit capable of optimizing heat exchanged amount of an internal heat exchanger in heating and cooling modes.